Question

radiation with successful adaptation in case of insects is result of

Answer 1

Insects and plants have diversified over roughly the same time intervals, and many insect host-affiliations are evolutionarily conserved, thus reflecting long-term, phylogenetic history. Rather than accumulating herbivores at a rate proportional to their geographic area of distribution or biomass, some plant groups post apparent chemical barriers to potential herbivore colonists, and seem accessible to relative few insect lineages, possibly preadapted by use of chemically similar or related hostplants. Evolutionary innovations in plant defenses and in insect feeding habits seem to have spurred their respective adaptive radiations, thus ecological opportunity may influence long-term evolutionary success. The greater diversity of insects and plants in the tropics probably reflects the greater age of tropical habitats as well as climatic barriers that limit successful invasion of the temperate zone to just those primitively tropical groups able to evolve strategies for both over-wintering and use of temperate resources. Successful invasion of the temperate zone may promote subsequent radiations of both insects and plants. Much of the available evidence from systematics is consistent with Ehrlich and Raven's (1964) suggestion that much of insect and plant diversification has been spurred by a series of ecological opportunities over evolutionary time. -from Authors